1. Field of the Invention
The present invention pertains to remote control of computers and more particularly to an interface between joystick and switch input devices as utilized in remote control environments and to a serial port of a personal computer.
2. Background Art
In computer systems, many methods of receiving information from the utilizer or user are employed, such as the use of serial input/output ports, parallel input/output ports, keyboards, bus expansion slots, cartridge slots, mouse ports, and joystick ports.
It is also possible by means of appropriate interface circuitry to utilize analog joysticks (these typically have four analog inputs and four switches to input into a standard RS232 serial computer port. This is a standard Electronics Industry Association serial port for use with computers). An arrangement for utilizing the ROM cartridge slot of a computer is taught by my U.S. Pat. No. 4,868,780 which issued on Sep. 19, 1989 and is assigned to the same assignee as the present application.
In the present application it is desirable for the interface to be powered by the port which it is accessing, eliminating the need for extra cables or power supplies. Such an arrangement permits the present invention to be utilized on a variety of computers. Examples of computers with which this kind of arrangement may be operated include the PC brand 286/12, the Atari 520ST, and Commodore Amiga 500. In addition, it should be noted that almost any IBM compatible personal computer usually includes a serial port built in like those described in the previous models. It is also relatively simple to add such an arrangement to computers not so equipped by means of a Jamico RS232 serial input card specifically designed for use with IBM PC/XT/AT/386 and compatible computers.
If a computer program requires the ability to receive analog inputs, a circuit is typically required to convert such inputs into a digital value and present that value to the computer, through use of one of its various methods of input. The switch positions may be converted to a logic level and then presented to the computer again through one of the above methods of input.
Some computers may not have provision for a joystick input. On the other hand, some computers do have joystick ports that allow only the input of a switch or digital data, such as up/down, right/left. Thus, while some computers have analog joystick inputs, a lack of standards requires the design of different joysticks for each computer. Accordingly, it is the purpose of the present invention to provide circuitry that can be utilized to input joysticks and switch positions into electronic industry standard RS232C ports, and therefore to be used with a variety of different computer types.